I was on a website today and was looking for rockwool and ran across a product called Higromite. Has anyone tried this? Is it similar to diatomite? Here is a link to the product: Higromite
If you dig deeply enough in their website, you'll see that it is a mixture of diatomaceous earth and volcanic ash, whereas diatomite is essentially 100% diatomaceous in nature.
I would imagine that it would be pretty much interchangeable with diatomite as a medium additive.